Ovenized crystal oscillators are well known in the art. These devices typically comprise a piezoelectric device such as a quartz crystal, the frequency-temperature characteristics of which are well known. The piezoelectric device is typically enclosed in an oven-like structure that is heated by some means so as to elevate the temperature of the piezoelectric device to a predetermined temperature at which its resonant frequency is most stable.
For optimum frequency stability, the piezoelectric device in an OCO is kept in a relatively narrow range of temperatures at which the output frequency of the piezoelectric device is stable. A temperature sensing mechanism is frequently used in a closed loop feedback system to control the amount of heat input to the oven in order to keep the temperature and hence the frequency of the piezoelectric device stable over time.
For many quartz crystals, the temperature at which the quartz must be kept, to have its frequency be stable is relatively high. A so called SC-cut crystal has a very stable output frequency near 80 degrees centigrade, a temperature at which the resonant frequency of the crystal is extremely stable. Unfortunately, consistently maintaining such a high temperature in a OCO used in a modern radio, for example, uses large amounts of power and has a long temperature settling time (the time it takes for the temperature inside the oven to stabilize). Additionally other temperature-sensitive semiconductor components located close by the oven might require thermal isolation from the oven to protect them from the heat transfered from the OCO that can adversely their performance.
In the past, thermally isolating an OCO by physically separating the OCO and its associated circuitry from large, heat-sinking circuit boards has reduced the temperature settling time and reduced the power required to raise and keep the oven at a high temperature. In addition, such a physical separation, accomplished by using either stand-offs, or by otherwise relocating the OCO away from temperature-sensitive devices has help to thermally isolate temperature-sensitive components from a high-temperature oven.
Mounting an OCO on its own circuit board, which is then typically mounted on standoffs that are connected to a main circuit board creates problems in the manufacture and assembly of both such boards, in addition to creating problems interconnecting the signals to and from the OCO board, to other circuits on the main circuit board. Accordingly a solution to the thermal isolation of a OCO on a circuit board would be an improvement over the prior art.